Immobilization of oyster drills in oyster beds



United States Patent 3,433,877 IMMOBILIZATION F OYSTER DRILLS IN OYSTER BEDS William Eric Ashton, Niagara Falls, and Edward D. Wei],

Lewiston, N.Y., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y., a corporation of New York No Drawing. Filed July 15, 1965, Ser. No. 472,348 US. Cl. 424-353 1 Claim Int. Cl. A01n 9/30; A01k 61/00 ABSTRACT OF THE DISCLOSURE Oyster drills, which are normally found in oyster beds, are immobilized, thereby preventing their attacking oysters. Such immobilization is effected by applying to the drills a granular composition containing to 80 percent of a mixture of trichlorobenzene, tetrachlorobenzene and pentachlorobenzene, on a low volatile matter attapulgus clay of low water disintegration rate and particle size in the range of about 4 to 50 mesh.

This invention relates to new and improved compositions for the control of marine predators, especially oyster drills, which are detrimental to commercial oyster beds. It also relates to methods of controlling such predators by utilizing such compositions.

Oyster production in the territorial waters of the United States is a major industry and it is currently estimated that some 20,000,000 to 30,000,000 bushels of oysters are gathered each year. However, in major oyster farming areas, production is becoming increasingly threatened by natural predators and in some areas production is actually declining for this reason, despite concerted efforts by oyster growers. The predators are marine animals, such as oyster drills and Starfish. Also harmful are competitive organisms, such as barnacles, tunicates, worms, hydroids, and protozoa, which foul the cultch on which the oysters are set.

Mechanical methods of removing or discouraging these predators and fouling organisms have been employed but have proved expensive and are not satisfactorily effective.

'In the earlier part of the life cycle of the oyster, the free swimming immature animal seeks a solid object on the sea bottom and becomes attached thereto. In oyster farming, the grower deliberately supplies solid material on which the oyster may set. This solid material is known as cultch. Cultch is most commonly mollusc shells, but can be of other materials, too, such as pieces of wood, gravel, roofing tile, wire or plastic.

It has been found by Loosanotf et al. in US. Patent 3,103,202 that by applying a mixture of trichlorobenzene, tetrachlorobenzene and pentachlorobenzene to the cultch, predation was reduced in the early development of the oyster bed, i.e., for a period of about two to three weeks. However, this method has proved ineffectual for the control of drills and other shell fish predators which invade the oyster beds later in the maturation of the oyster, i.e., in the period of about three years from set to harvest.

Limited success has been attained by applying mixed polychlorobenzenes to dry sand, placing this on the deck of a boat and flushing it overboard onto the oyster beds (usually employing a fire hose). There are several serious disadvantages to the above method, including the followmg:

(a) Application is diflicult and not uniform;

(b) Dry sand is required in large volume (35 cubic yards per acre) and this is difiicult to obtain in many areas;

(c) The gross weights involved, because of the low carrying capacity of the sand are extremely large, permitting only small areas to be treated at a time;

(d) It has been necessary to formulate at the application site in order to avoid the expense of shipping the large amounts of dilute formulation for any distance.

There is a need for a highly concentrated formulation which will fulfill the requirements of dropping to the bottom of the ocean and resisting disintegration by the underwater currents, while releasing the toxicant at a rate suitable for predator control. The requirements for stability of the product and controlled toxicant release are to some extent contradictory. Applicants have discovered unobvious materials which possess both these properties and have invented the present compositions comprising them. Applicants have found that the same materials, i.e., polychlorobenzenes, such as trichlorobenzene, tetrachlorobenzene and pentachlorobenzene isomers and mixtures thereof, can be made highly effectual against drills and other oyster predators, in the newly discovered compositions, and have discovered numerous other advantages of such compositions.

In accordance with the present invention, a composition effective against oyster bed predators, especially drills, comprises an effective proportion of a polychlorobenzene, especially trichlorobenzene, tetrachlorobenzene, or pentachlorobenzene, or a mixture thereof, and a granular clay of a particular critical type (low volatile matter). It also is of a method for combating said predators which comprises applying said composition in an effective amount to the oyster bed or its periphery.

The clay employed in the methods and compositions of the invention is broadly describable as a granular fullers earth. The preferred variety of fullers earth from the standpoint of the present invention is attapul gite of the low volatile matter (LVM) type. By attapulgite is meant the sorptive aluminum magnesium silicate of the Hawthorne Formation, a geologic clay formation extending from the approximate location of Tampa, Fla., northwesterly to the Georgia-Florida border. Attapulgite is characterized mineralogically by Lapparent in Comptes Rendus, vol. 202, page 1728 (1936). Other fullers earths are workable but are inferior in performance to said IJVM attapulgite. By the designation LVM it is meant that the clay shall suffer a loss of weight less than 14 percent when ignited at 1,800 degrees Fahrenheit to constant weight.

A superior composition of the invention utilizes as the clay component of said formulation an LVM attapulgus clay having less than 22 percent disintegration under the conditions of the following standard test, taken from Interim Federal Specification (U.S.A.), tlnsecticide, Heptachlor, Granulated, dated Feb. 8, 1961:

GRAIN BREAKDOWN PROCEDURE Transfer the test sample (10 grams) to a 250 milliliter glass-stoppered graduated cylinder of conventional design, and make up to 250 milliliters volume with distilled water at ordinary room temperature (approximately 25 degrees centigrade). Rotate the cylinder end over end by machine for two hours at 30 revolutions per minute. Remove the cylinder from the tumbling machine, allow the cylinder to stand undisturbed for /2 hour and draw off by suction, and discard, any oil that has risen to the top. Support the cylinder upright in a clamp over the sieve so that the base of the cylinder is approximately centered within the sieve frame and is approximately one centimeter above the sieve cloth. The mesh size used in this test is 250 microns (US. Standard Sieve Size Number 60), and the sieve frame is eight inches in diameter, full length (two inches inside depth). Flow the sample out onto the sieve by means of a vigorous stream of tap water introduced through a hose extending down into the cylinder, nearly to the bottom. (If the last few grains persist in remaining in the cylinder, they may be removed by inversion of the cylinder, with the use of water but without hosing.) As soon as all of the sample has passed out of the cylinder, transfer the sieve residue to a filter by rinsing out the sieve with a gentle stream of water. Dry the residue at a temperature not exceeding 55 degrees centigrade, and calculate the percentage of sample passing through the sieve, the grain breakdown.

This testing method is to be used to evaluate the clay carrier itself, before impregnation, or the finished formulation after removal of the organic component by extraction with a solvent, such as benzene, chloroform, or the like. Clay showing less than about 22 percent breakdown by this standard test will hereinafter be designated, for brevity, as having a water disintegration rate of less than about 22 percent, without recitation of the test details.

The water disintegration test, when run on the completed formulation does not distinguish between formulations which were based on clay having a low water disintegration rate per se and those which were based on clay having a high water disintegration rate per se. It is, therefore, hard to understand why this factor is so important to the performance characteristics of the finished formulation, and the present inventors can offer no theoretical explanation for their finding. In general, the mode of action of the granular formulations of the invention upon the oyster bed predators is unknown. By its very nature, it is difficult to observe directly, and, therefore, theoretical explanations thereof are unconfirmed.

The composition of the invention may contain from about 5 percent up to the saturation point (about 80 percent) of a polychlorobenzene or mixture thereof, based on the weight of finished formulation. It is preferable not to load the carrier to the point of wetness, so that a preferred upper limit is the maximum absorptive capacity of the clay carrier at or below which point the formulation appears dry, e.g., 60 to 70 percent. The screen size of the clay is usually from about 4 to 50 mesh, United States Standard Sieve Series. The polychlorobenzenes to be used in the compositions of the invention are chlorine-substituted benzenes having from 1 to 6 chlorine atoms, preferably predominating in tri-, tetraand pentachlorobenzenes. These materials are not critical as to composition, but a typical effective composition, preferred because of low cost and ready availability, is the Polystream composition described in U.S. Patent 3,103,202. The product will typically fall within the range of to percent trichlorobenzene (1,2,4- and 1,2,3-isomers), 40 to percent tetrachlorobenzene (l,2,3,4- and 1,2,4,5-isomers), and the remainder will be pentachlorobenzene, lesser amounts of dichlorobenzenes, and trace amounts of monochlorobenzene and hexachlorobenzene.

The formulation of the invention may also contain other pesticidal and/or pest-repellent ingredients, such as, for example, 1 naphthyl N-methylcarbamate. In addition, other agents may be added, such as adhesives, resins, hydrophobes, coloring agents and de-tackifiers.

The compositions of the invention are distributed over the areas to be protected at a rate of 200 pounds per acre or more of active ingredient (polychlorobenzenes). A preferred application rate is from 300 to 2,000 pounds per acre of polychlorobenzene.

The following examples serve to illustrate the invention. They do not limit it. All parts are by weight.

Example 1.--Preparation of granular formulation A mixture of polychlorobenzenes of the following composition:

Percent 1,2,4-trichlorobenzene Hg: 29.9

1,2,3-trichlorobenzene 0.8 1,2,3,4,5-tetrachlorobenzene 6.1 1,2,3,4-tetrachlorobenzene 47.5 Pentachlorobenzene 10.1 Monoand dichlorobenzene 3.9

was sprayed onto a tumbling mass of attapulgus LVM clay granules having a water disintegration rate of 2.2 percent, until the formulation contained 40 percent polychlorobenzene by weight. The clay particles were of size to pass an eight mesh United States Standard Sieve Series Screen and remain on one of 24 mesh. Other formulations are made using attapulgite of 24 to 48 mesh size.

Example 2 A mixture of polychlorobenzenes of the following composition:

Percent l,2,3,4-tetrachlorobenzene 75.8 l,2,4,S-tetrachlorobenzene 6.3 Pentachlorobenzene 17.5

1,2,4-trichlorobenzene 0.4

was melted at about 60 degrees centigrade and was poured slowly onto a stirred mass of attapulgus LVM clay granules (having a water disintegration rate of 15 percent and a screen size of through 8 mesh on 15 mesh) until the granules contained 40 percent of the polychlorobenzenes by weight.

Example 3 A one-acre oyster bed area in Long Island Sound was used as a test plot. Onto the area in the month of Septemher were evenly distributed 1,650 pounds of 40 percent polychlorobenzene granular 8 to 15 mesh formulation, prepared by a method corresponding to that of Example 1, using LVM attapulgus clay having about a 15 percent Water disintegration rate by the standard test. The oysters'in the bed were 12 to 18 months old at the time of application. The treated bed was inspected by divers over a period of 5 to 6 weeks (until the end of the growing season) and the oyster drills, normally prolific in this area, were found immobile during that time. In an adjacent untreated oyster bed area, the drills were highly active and made great depredations on the oyster population.

Example 4 A treatment similar to that of Example 3 was effected but the formulation used had a water disintegration rate of greater than 22 percent. A diver inspected the plot shortly after treatment and found the bottom water to be milky in appearance from released polychlorobenzene and clay particles. When inspected two weeks later, the drills were more active than at the corresponding time in the procedure of Example 3 and some adverse drill effects had been caused on the oysters.

The invention has been described with respect to the specific aspects thereof. It is not to be limited thereby and it is intended that the claims cover the various aspects of the invention within the scope and that substitution of equivalents may be made without departing from the invention.

What is claimed is:

1. A method for the immobilization of oyster drills, normally found prolific in oyster beds, comprising applying to said drills in an oyster bed an effective amount of a granular composition containing from about 5% to about based on the weight of the finished formulation, of a polychlorobenzene mixture comprising predominately tri-, tetra-, and pentachlorobenzene, on a low volatile matter attapulgus clay, which clay loses less than 14 percent of its weight when ignited at 1,800 F. to constant weight, and which clay has a water disintegration rate which is less than 22 and is resistant to disintegration by under- 4 to 50 mesh.

References Cited UNITED STATES PATENTS Pra'hl 260-650 Wibaut 260-650 Hartshorne 167-42 XR Cross 167-42 Darragh 260-650 Weimer et a1 260-650 Eng et al. 260-651 Fleck et al 260-650 Marples et a1 167-42 XR Loosanoff et a1 119-4 Yaffe et a1 167-42 US. Cl. X.R. 

